Lapping machine



March 21, 1961 R. BALDRIDGE LAPPING MACHINE 4 Sheets-Sheet 1 Filed Oct; 8, 1956 INVENTOR. fidrcazd fiaza 7' R. BALDRIDGE LAPPING MACHINE March 21, 1961 4 Sheets-Sheet 2 5 Filed. Oct. 8, 1956 March 21, 1961 R. BALDRIDGE LAPPING MACHINE 4 Sheets-Sheet 3 Filed Oct. 8, 1956 R m w W.

March 21, 1961 R. BALDRIDGE LAPPING MACHINE Filed Oct. 8, 1956 4 Sheets-Sheet 4 VEN TOR LAPlPING MACHINE Ronald Baldridge, 1745 Wabasso Way, Glendale, Calif.

Filed Oct. 8, 1956, Ser. No. 614,412

16 Claims. (Cl. 51--124) This invention relates to the art of producing flat surfaces on hard materials by abrading such surfaces, and more particularly to a machine for producing such surfaces on largepobjects of which granite surface plates or other mineral or metallic objects which are required to have a large surface which is flat within extremely narrow limits are examples.

The principal object of the invention is to provide a lapping type of machine for grinding flat surfaces on large stone or metallic elements; said machine generally comprising a large wheel or table rotatable about a vertical axis upon which the article to be operated upon rests and is restrained against rotation with the wheel and whereby, due to the weight of the article, the relative rotation between the wheel and the articles and the introduction of suitable abrasive on the surface of the wheel, the desired flat surface can be generated on the wheel contacting face of the article.

Another object of the inventionis the provision of an article supporting wheel for a machine of the above character which is especially constructed to have the necessary rigidity in the presence of a load thereon of the order of many tons to produce a flat surface within limits of the order of .00005".

A further object of the invention is to provide a machine for lapping large flat surfaces including a vertical axis wheel or table upon which the work lies and including provisions for adjustment of the support for the wheel whereby the work engaging face of the wheel may be maintained in a desired degree of flatness.

Still another object of the invention is to provide a machine for lapping large flat surfaces including a wheel or table rotatable about a vertical axis and upon which the work lies together with work engaging means effective to prevent the work from rotation with the wheel while allowing the frictional engagement of the work with the wheel to cause non-synchronous rotation of the work atent O about a vertical axis bearing forming a part of the work other objects and advantages as may subsequently appear,

the invention resides in the parts, and in the construction, combination and arrangement of parts described,

by way of example, in the following specification disclosing a presently preferred embodiment of'the invention; reference being had to the accompanying drawings which form a part of said specification and in which drawings:

Fig. l is a top plan view of a lapping machine embodying the invention showing the several portions of the a 2,975,564 Patented Mar. 21, 1961 machine mounted on a foundation common to all of the said portions,

Fig. 2 is a side elevation of the right hand side of the machine as viewed from a position in which the boom actuating means is at the left of the viewer.

Fig. 3 is an enlarged scale, sectional plan view taken on the line 3--3 of Fig. 2,

Fig. 4 is an enlarged scale, medial sectional view of the boom actuating crank pin taken on the line 4-4 of Fig. 1,

Fig. 5 is a vertical sectional view of the lapping wheel, its bearing support and drive means; the view being taken on the angled line 5-5 of Fig. 1,

'Fig. 6 is an enlarged top plan view of the lapping wheel with portions thereof being broken away to show details of interior construction as well as of the bearing support therefor,

Fig. 7 is an enlarged scale side elevation of one of the supporting bearings for the lapping wheel,

Fig. 8 is an end elevation as viewed from the left hand end of Fig. 7,

Fig. 9 is a top plan view of the work piece holding frame,

Fig. 10 is a sectional view taken on the staggered line 1tl10 of Fig. 9 and additionally showing the engagement by the pivot pin carried by the boom,

Fig. 11 is an enlarged sectional view of one of the adjusting means of the work piece holding frame; the view being taken on the line 11-11 of Fig. 9, and

Fig. 12 is a side elevation of the work holding frame engaging pivot pin carried by the boom.

Generally, the machine comprises three units mounted in proper relation on a common foundation; the said three units comprising the lapping wheel with its supporting bearings and driving means, the boom, the work engaging means carried thereby and its supporting post, the boom oscillating means and its drive and positioning means and these units will be described separately.

The lapping wheel unit and drive means The lapping wheel 1 is of welded steel construction and is of suflicient depth to have the necessary rigidity to withstand the loads placed thereon. For example, a block of granite approximately 6 X 8" and 18" thick is in the upper range of sizes which the illustrated machine can operate on and will weigh about 6 /2 tons. As will be later discussed, this weight is generally disposed at one side of the axis of the wheel and it must not cause any deflection in the surface of the wheel upon which it rests if the desired flatness of the surface of the block is to be achieved. To this end, the wheel comprises a central vertical tube 2 extending between a bottom plate 3 and a top plate 4 and constituting a first circular wall. Radiating from the tube 2 are rib members 5 which are held in spaced relation by transversely extending wall sections 6, 7 and 8; the latter forming the outer side surface of the wheel. Also between the wall sections 7 and 8 are additional rib members 9 arranged in pairs in each of the cells bounded by an adjacent pair of the ribs 5 and the interconnecting wall sections 7 and 8; said additional rib members being disposed with one edge each at the juncture with the wall member 7 with adjacent ribs and having their opposite side edges joined to each other and to adjacent wal-l member 8 midway between the rib members (see Fig. 6). All of these members, including the top and bottom plates, the wall members, the rib members and the additional rib members are Welded together at all points of contact and form a wheel construction which is readily manufactured and which is extremely rigid.

The bottom plate 3 at its center carries a heavy circular block 10 welded to the under side of the plate and the block in turn carries a depending stub shaft 11 disposed in the axial line of the wheel; said shaft being engaged by a ball bearing 12 carried by a support 13 on the base plate 14 for'the'wheel unit which base plate is mounted on the foundation for ,the'machine. The support for the wheel on the base plate comprises a series of tapered rollers 15 engaging a flat circular track 16 secured to the under side of the plate 3 and in the illustrated embodiment disposed slightly inwardly of the wall members 7; said rollers having their major and minor diameters proportionate to the inner and outer diameters of the track 16 and the axes of said rollers being disposed in vertical planes cutting the axis of the wheel and being inclined upwardly inwardly in said planes to'an extent at which the upper surface of the rollers form a line contactwith the track 16. Each of said rollers is mounted in a separate bearing bracket 17 disposed directly beneath the track 16 and comprising a base portion 18 fixed to the base plate 14, thence extending parallel to and spaced from the base plate in the direction of rotation of the wheel and terminating in ear portions 19, 19 in which the shaft 20 on which the roller 15 rotates is mounted. Directly beneath the ear portions 19, 19, the base portion 18 carries depending screws 21, 21 with the heads thereof engaging the base plate 14. By adjusting these screws with attendant springing of the base portion 18, the individual rollers can be adjusted vertically to extents that assure the flatness of the upper surface of the wheel. It is to be noted that the said rollers are the sole support of the Wheel and that the sole function of the stub shaft 11 is to establish the axis of rotation of the wheel. Rotation of the wheel can be obtained by any convenient drive; the illustrated drive comprising a bevel pinion 22 mounted'on a shaft 23 which is journaled in a bearing bracket 24 mounted on the base plate 14; said pinion Emeshing with a ring gear 25 fixed to the under surface of the plate 13 and disposed inwardly of the track 16. The shaft 23 may be driven by any desired means such as the motor 26 and speed reducer 27 interposed between the motor and shaft; said motor and speed reducer being mounted on the machine foundation at some convenient point beyond the outer perimeter of the wheel with the shaft disposed in a line extending radially of the axis of the wheel. The grinding or lapping surface of the wheel comprises a plurality ofheavy segmental plates 28 removably secured to the plate 4 by screws 29; said plates being spaced from each other withresultant formation of channels 30 in which excess grinding compound and the comminuted material of the work piece is collected and'gradually transported to the rim of the wheel by centrifugal force deriving from rotation of the wheel. These plates may be of any material suitable for the lapping operation such as cast iron or steel of a desired degree of hardness. For some purposes, these plates may even be formed from a hard stone such as granite or of a material sufiiciently soft to become charged with the abrasive grains.

The boom, boom support, and work engaging means Mounted on a base plate 31 secured to the foundation at one side of the wheel 1 is a vertical post '32 formed from an I-beam having a flat side 34- thereof disposed toward the wheel 1. Braces 33 extending from the base plate 31 to the upper end of the post 32 serve to secure it against bending movement relative to the base plate 31.

The flat face 34 of the post disposed toward the wheel 1 carries a saddle member 35 mounted for vertical adjustment thereon and secured in adjusted position by 'set screws 36 threaded into flange portions 37, 37 of the saddle 35 which extend around the edges of the post and are disposed in rear of the flange of the post constituting the flat face 34 '(see Fig. 3). The face of the saddle opposite the post engaging surface thereof is provided with vertically spaced ears 38 and 39 and mounted in the said ear portions is a vertically disposed pivot bolt 40 on which the ears 41 and 42 of the boom supporting bracket member 43 are mounted for free swinging movement. One end of the boom 44 is fixed to the lower portion of the bracket 43 and a diagonal brace 45 extends from the boom 44 to the upper portion of the bracket 43. The boom 44 is preferably of hollow rectangular or box cross section and extends horizontally from the bracket 4-3 to a free end disposed a considerable distance beyond the side of the wheel opposite the side adjacent to the post 32 and the said free end is connected to the actuating means hereinafter to be described in detail.

Mounted for adjustment along the boom is a pivot pin means for engaging the Work holding means; said pivot pin means comprising a base element 46 engaging one vertical face and the top and bottom faces of the boom. A clamp plate 47 engages the opposite vertical face of the boom and is secured to the upper and lower flanges of the base element 46 by screws 48 by which the base element 46 is secured in the desired fixed position along the boom 44. The base element 46 carries a vertical threaded sleeve portion 46' in which the threaded portion of a pivot pin member 49 is mounted; said pivot pin member terminating below the sleeve portion 46 in a cylindrical bearing pin 49 engageable with the work holding frame 50 and above the sleeve portion 46 the pivot pin member 49 canries a crank by which it may be rotated to move it vertically into and out of engage ment with the work holding frame. The upper end of the threaded portion of the pivot pin member 49 also carries a lock nut 51 which engages the upper end of the sleeve portion 46 and serves to prevent dislodgement of the member 49 while in engagement with the work holding frame.

The work holding frame comprises a socket member 52 having a vertical bore 53 adapted to 'be engaged by the bearing pin end 49' of the pivot pin member 49; said socket member having four tubular arms extending radially therefrom and comprising two diametrically opposite shorter arms 54, 54 and two diametrically opposite longer arms 55, 55 disposed at right angles to the said shorter arms. At their free ends, each of the said tubular arms carries an adjustable work engaging means and since they are identical, the description of one of them will suffice. At its free end the tubular member carries a collar 56 which is cut oif flush with the under side of the tubular member; At its upper side, the collar 56 is provided with a threaded hole extending through the tubular member in which a set screw 57 is disposed. Slidably disposed in the tubular member is a sleeve58 which extends beyond the free end of the tubular member and at its end beyond said tubular member carries a depending arm 59 having a work engaging screw 60 extending therethrough in a plane containing the axial line of the sleeve; said screw having a loosely mounted work' engaging member 61 at its inner end and a polygonal head at its outer end affording means for turning the screw by a wrench. Additionally, the screw 60 carries a lock nut 62 engageable with the arm 59 to hold the screw in set position. The sleeve 58 at its upper face is provided with a series of spaced sockets 63 into which the set screw 57 may be selectively engaged. In use, the work piece, such as a block of granite is placed upon the wheel 1 and the work holding frame is suitably adjusted and secured to the 'sides' of the blockso that the socket bore53 is disposed substantially at the vertical centerline of the block. Assuming that the pivot pin holding means is positioned at the desired position longitudinally of the boom and that the boom is set at the desired vertical'position, the block is positioned so that the pivot pin will enter the socket bore. This may be by relative movement ofthe'wheel and boom or it' may, in part,include the shifting of the block on the wheel. When the frame and pivot pin are side of the frame.

aligned and interengaged, the machine is ready for operation except for such adjustment of the boom oscillating means as may be necessary.

The boom oscillating means and drive The means for imparting oscillating motion to the boom comprises a vertical axis crank disc 64 which is carried by the upper end of a shaft 65 journalled in a frame 66 and driven through suitable gearing within the frame by a motor 67 mounted on a bracket 68 at one Fixed to the upper face of the disc 64 are parallel members 69, 69 having opposed ledges 70, 70 spaced from the surface of the disc and defining a T-slot 71 extending diametrically across the face of the in which the head 72 of a crank pin bolt 73 is received. The shank of the bolt extends through a bottom Washer 74 lying on the members 69, 69 thence through the inner races of a pair of ball bearings 75,

j 75 thence through the first top washer 76 and a second top washer 77 and terminates in a threaded portion 78 engaged by lock nuts 79, 79. The washers 74 and 76 are provided with annular shoulders 80 and 81 which engage the said inner races and clamp them against rotation, when the nut is tightened; the remainder of the surfaces of the washers adjacent to the ball bearings being relieved (see Fig. 4).

The outer races of the ball bearings are encircled by a collar 82 secured thereto by set screws 83, 33 and the collar at one side thereof is provided with spaced parallel arms 84, 34 between which one end of an extensible link component '85 is pivotally connected by a bolt 66. The link component 85 is provided with a series of spaced holes 37 and is connected by bolts 88, 88 to a second link component 89 having similarly spaced holes whereby the said components may be interconnected to form a desired length of link. The other end of the link component is pivotally connected by a bolt 90 between parallel arms 91, 91 of a collar member 92 which is clamped to the lower end of a vertical shaft 93 journalled in a sleeve 94 carried by a base member 95 which is mounted adjacent the free end of the boom and secured in adjusted position thereon by a clamp plate 96 in the same manner as the base element 46.

The frame 66 is mounted on a pair of spaced rails 97, 97 carried by the foundation and positioned preferably at right angles to a line containing the axis of the wheel and the post 32; said frame being movable along said rails by any convenient means such as the lead screw 93 operated by the crank 99 and held against endwise movement by the bearing block 160 secured to the foundation; said adjustment serving to shift the path of reciprocation of the work piece longitudinally of said path. Since the bolts 86 and 9t) are at right angles to the crank pin assembly and the shaft 93, the link will accommodate a wide range of this-alignment.

Operation of the machine Assuming that the machine has been installed and that the wheel has been leveled and the upper surf-ace lapped to the desired degree of flatness, a sawed block of granite is placed on the wheel and the work holding frame applied thereto. The wheel and boom are each moved by increments selectively or the block and frame are shifted on the wheel until the bearing pin 49' is aligned with the bore 53 in the work holding frame 50 and the bearing pin is then screwed down to effect interengagement with the frame and locked by the nut 51. The wheel is then caused to rotate in a clockwise direction as viewed in Fig. l and simultaneously the crank disc is rotated to impart oscillation to the boom. The surface of the wheel is constantly supplied with abrasive powder and water to effect the grinding or lapping action on the block and the rotation of the wheel through the differential frictional drag on the block at points closer andfarther from the axis of the Wheel will cause the block and frame to rotate in a clockwise direction about" the axis of the pivot pin and the extent of oscillation of the boom together with the position of the boom oscillating means on its tracks being adjusted so that the block is moved at least to and preferably across the axis of the wheel to maintain flatness in the entire surface of the wheel. As the grinding action progresses, successively finer grades of abrasive may be used until the desired finish is achieved; it being preferable to begin the operation with a coarse abrasive. The change in abrasive does not require stopping the machine as the coarser grains are soon broken down to finer sizes by the pressure of the work piece on the wheel. It is preferable to adjust the boom so that when moved toits outermost position, the end of the block will project beyond the edge of the wheel so that from time to time the machine can be stopped with the block overhanging the edge to permit inspection of the surface being ground and determination of the progress of the work without the necessity of lifting the block from the machine for that purpose. Since the block is both rotating and sliding on the surface of the rotating wheel, inspection of any portion of the lapped surface will accurately indicate the condition of the whole surface. Where the block is to be finished to extremely close tolerances, and especially .if the block is of large size, it may be necessary to remove the block from the machine to measure the fiatness thereof and either return the block to the machine for further lapping or to complete the lapping with a machine such as shown in my prior Patent No. 2,690,636 when the tolerance over the entire surface of the block, is, say, 0.00002" or less.

While the foregoing specification discloses a presently preferred form of the invention, it is not to be inferred therefrom that the invention is limited to the exact form thereof above disclosed by way of example, and it will be understood that the invention embraces all such changes and modifications in the parts, and in the construction, combination of parts as shall come within the purview of the appended claims.

I claim:

1. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving, abrading surface, a base, a wheel disposed for rotation about a vertical axis and having a fiat upper surface constituting a lapping surface mounted on said base, a first bearing means carried by said base and engaging said wheel and establishing only the said vertical axis of rotation of said Wheel, a. second bearing means carried by said base and affording vertical support for said wheel; said second bearing means comprising a series of tapered rollers each mounted on a separate stationary base and said rollers being disposed in a circumferentially spaced relation about the axis of said wheel and with the axes of said rollers being in vertical planes radial to said axis of said wheel and being so angularly disposed in said vertical planes that the uppermost portions of the peripheries of said rollers are disposed tangentially to a common plane normal to the axis of said wheel, and a ring member on the under surface of said Wheel disposed coaxially to the axis thereof and having a flat bottom surface in said common horizontal plane resting on all of said rollers; said ring member having a radial dimension which is less than the radial dimension of said wheel, means for rotating said wheel, and means for holding a work piece on said lapping surface of said wheel and for imparting reciprocating movements to the work piece while resting on said rotating lapping surface; said work piece holding means including devices permitting free rotation of the Work piece about a vertical axis While engaged by said holding means, and means for imparting said reciprocatory movement to said work holding means.

2. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a "moving, abrading surface, a wheel disposed for rotation stituting alapping surface, separate bearing means for establishing, respectively, the said axis of rotation and the vertical support of said wheel, said wheel comprising an integral structure including parallel, spaced top and bottom plates, a series of radially spaced ribs and transversely extending wall members integrally united to said plates and to each other at all points of juncture with resultant formation of a wheel structure of extreme rigidity; said wheel further including a series of plates fixed to the top surface of said top plate and constituting the lapping surface of said wheel, means for rotating said wheel on said axis and means for holding a work piece on said lapping surface of said wheel and for imparting reciprocating movements to the work piece while resting on said rotating lapping surface; said work piece holding means including devices permitting free rotation of the work piece about a vertical axis while engaged by said holding means, and means for imparting said reciprocatory movement to said work holding means.

3. In a machine for lapping fiat surfaces on objects disposed with the surface thereof to be lapped resting on a moving, abrading surface, a wheel disposed for rotation about a vertical axis and having a flat upper surface constituting a lapping surface, separate bearing means for establishing, respectively, the said axis of rotation and the vertical support of said wheel, said wheel comprising an integral structure including parallel, spaced top and bottom plates, a series of radially spaced ribs and transversely extending wall members integral-1y united to said plates and to each other at all points of juncture with resultant formation of a wheel structure of extreme rigidity; said wheel further including a series of plates fixed to the top surface of said top plate and constituting the lapping surface of said wheel, means for rotating said wheel on said axis, work piece engaging means disposed above said wheel including a vertical axis bearing element affording free rotation about the axis thereof of a Work piece resting on said lapping surface and engaged by said Work piece engaging means, and power means for imparting reciprocatory movement to said work engaging means in a plane substantially parallel to the plane of said lapping surface with resultant reciprocation of a work piece by said work piece engaging means on said lapping surface in a path equal in length to at least a portion of the diametral dimension of said wheel.

4. In a machine for lapping flat surfaces on objects disposed With the surface thereof to be lapped resting on a moving, abrading surface, a base, a Wheel disposed for rotation about a vertical axis and having a flat upper surface constituting a lapping surface mounted on said base, a first bearing means carried by said base and engaging said wheel and establishing only the said vertical axis of rotation of said Wheel, a second bearing means carried by said base and affording vertical support for said wheel; said second bearing means comprising a series of tapered rollers each mounted on a separate stationary base and said rollers being disposed in a circumferentially spaced relation about the axis of said wheel and with the axes of said rollers being in vertical planes radial to said axis of said wheel and being so angularly disposed in said vertical planes that the uppermost portions of the peripheries of said rollers are disposed tangentially to a common plane normal to the axis of said wheel, and a ring member on the under surface of said wheel disposed coaxially to the axis thereof and having a. flat bottom surface in said common horizontal plane resting on all of said rollers; said ring member having a radial dimension which is less than the radial dimension of said wheel, means for rotating said wheel, work piece engaging means disposed above said wheel including a vertical axis bearing element affording free rotation about the axis thereof of a work piece resting on said lapping surface and engaged by said ;work piece engaging means, and power means for imparting reciprocatory movement to said Work engaging means in a plane substantially parallel to the plane of said lapping surface with resultant reciprocation of a work piece by said work piece engaging means on said lapping surface in a path equal in length to at least a portion of the diametral dimension of said Wheel.

5. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a wheel mounted for rotation about a vertical axis upon hearing means disposed wholly beneath said wheel and said wheel having a flat upper surface constituting a lapping surface for work pieces placed thereon, means for rotating said wheel about said axis, means for holding a work piece on said lapping surface against rotation with said wheel, and means for imparting reciprocatory movement to said work holding means and a Work piece held thereby in a path generally transverse to the direction of movement of said wheel; said movement imparting means including adjustable devices operable to adjust the position of said path in directions generally normal to the longitudinal direction of said path.

6. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a Wheel mounted for rotation about a vertical axis upon bearing means disposed wholly beneath said wheel and said wheel having a flat upper surface constituting a lapping surface for work pieces placed thereon, means for rotating said wheel about said axis, means for holding a work piece on said lapping surface against rotation with said wheel, and means for imparting reciprocatory movementto said work holding means and a Work piece held thereby in a path generally transverse to the direction of movement of said Wheel; said movement imparting means and work piece holding means comprising a boom extending across said wheel and disposed above said wheel a distance greater than the thickness of a work piece and having one end thereof mounted for movement about a vertical axis at one side of said Wheel, Work piece engaging means connected to said boom, means for oscillating said boom about said pivotal mounting with resultant reciprocatory movement of a Work piece held by said work piece engaging means on said lapping surface, and devices for shifting said boom oscillating means to desired positions along a line tangent to the arc of oscillation of the free end of said boom with resultant change in the position of the path of oscillation of said boom without significant change in the length of the path of oscillation thereof.

7. In a machine for lapping fiat surfaces on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a Wheel mounted for rota tion about a vertical axis upon bearing means disposed Wholly beneath said wheel and said wheel having a flat upper surface constituting a lapping surface for Work pieces placed thereon, means for rotating said wheel about said axis, means for holding a work piece on said lapping surface against rotation with said wheel, and means for imparting reciprocatory movement to said work holding means and a work piece held thereby in a path generally transverse to the direction of movement of said wheel, said movement imparting means and work piece holding means comprising a boom extending across said wheel and disposed above said wheel a distance greater than the thickness of a Work piece and having one end thereof mounted for movement about a vertical axis at one side of said wheel, work piece engaging means connected to said boom, and means at the opposite side of said wheel comprising a vertical axis shaft and supporting bearing means therefor disposed at the side of said wheel opposite said pivotal mounting of said boom, means for driving said shaft, a crank pin on said shaft, and a link connecting said crank pin with the adjacent pivotal mounting with resultant reciprocatory movement 9 of a work piece held by said work piece engagingmeans on said lapping surface.

8. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a wheel mounted for rotation about a vertical axis upon bearing means disposed wholly beneath said wheel and said wheel having a flat upper sur face constituting a lapping surface for work pieces placed thereon, means for rotating said wheel about said axis, means for holding a work piece on said lapping surface against rotation with said wheel, and means for imparting reciprocatory movement to said work holding means and a work piece held thereby in a path generally transverse to the direction of movement of said wheel; said movement imparting means comprising a boom mounted for oscillation about a vertical axis pivot at one side of said wheel and thence extending across said wheel and having connection with rotary means at the opposite side of said wheel effective to impart oscillation of said boom about said pivot, and said work piece holding means comprising a vertically disposed bearing pin mounted on said boom between said pivotal mounting and said connection with said rotary means and a work piece engaging frame comprising a vertical axis socket freely rotatably engaging said bearing pin with freedom of relative axial movement and a series of arms carried by said socket extending laterally therefrom and terminating in devices operable to engage the sides of a work piece with said socket disposed substantially at the vertical centerline of the work piece; the oscillation of said boom being effective to move a work piece held by said work holding means back and forth in a path substantially transverse to the direction of movement of the portion of the lapping surface engaged by the work piece and said engagement of said bearing pin and said socket permitting the work piece to rotate about the axis of said bearing pin in response to the differential frictional drag thereon deriving from the engagement with larger and smaller diameters of said lapping surface.

9. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a wheel mounted for rotation about a vertical axis upon bearing means disposed wholly beneath said wheel and said wheel having a flat upper surface constituting a lapping surface for work pieces placed thereon, means for rotating said wheel about said axis, means for holding a work piece on said lapping surface against rotation with said wheel, and means for imparting reciprocatory movement to said work holding means and a work piece held thereby in a path generally transverse to the direction of movement of said wheel; said movement imparting means and work piece holding means comprising a boom extending across said wheel and disposed above said wheel a distance greater than the thickness of a work piece and having one end thereof mounted for movement about a vertical axis at one side of said wheel, work piece engaging means connected to said boom, and means for oscillating said boom about said pivotal mounting with resultant reciprocatory movement of a work piece held by said work piece engaging means .on said lapping surface; said work piece engaging means being longitudinally adjustable along said boom with resultant adjustment of said path laterally of the longitudinal direction thereof.

10. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a wheel mounted for rotation about a vertical axis upon bearing means disposed Wholly beneath said wheel and said wheel having a flat upper surface constituting a lapping surface for work pieces placed thereon, means for rotating said wheel about said axis, means for holding a Work piece on said lapping surface against rotation with said wheel, and means for irn parting reciprocatory movement to said work holding means and a work piece held thereby in a path generally 1O transverse to the direction of movement of said wheel; said movement imparting means and work piece holding means comprising a boom extending across said wheel and disposed above said wheel a distance greater than the thickness of a work piece and having one end thereof mounted for movement about a vertical axis at one side of said wheel, work piece engaging means connected to said boom, and means engaging the other end of said boom for oscillating said boom about said pivotal mounting with resultant reciprocatory movement of a work piece held by said work piece engaging means on said lapping surface said means for oscillating said boom comprising a vertical axis shaft and supporting bearing means therefor and carrying a radially adjustable crankpin and a link connecting said crankpin with the end of said boom opposite the pivotal mounting thereof; the radial adjust-, ment of said crankpin serving to vary the extent of oscillation of said boom and the resultant reciprocatory movement imparted to a work piece.

11. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a wheel mounted for rotation about a vertical axis upon bearing means disposed wholly beneath said wheel and said wheel having a flat upper surface constituting a lapping surface for work pieces placed thereon, means for rotating said wheel about said axis, means for holding a work piece on said lapping surface against rotation with said wheel, and means for imparting reciprocatory movement to said work holding means and a work piece held thereby in a path generally transverse to the direction of movement of said wheel; said movement imparting means and work piece holding means comprising a boom extending across said wheel and disposed above said wheel a distance greater than the thickness of a work piece and having one end thereof mounted for movement about a vertical axis, work piece engaging means connected to said boom, and means for oscillating said boom about said pivotal mounting with resultant reciprocatory movement of a work piece held by said Work piece engaging means on said lapping surfaces; said pivotal mounting for said b oom having capacity for vertical adjustment and said boom oscillating means including devices effective automatically to compensate for said vertical adjustment of said boom.

12. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a wheel mounted for rotation about a vertical axis upon bearing means disposed wholly beneath said wheel and said wheel having a fiat upper surface constituting a lapping surface for work pieces placed thereon, means for rotating said wheel about said axis, means for holding a work piece on said lapping surface against rotation with said wheel, andmeans for imparting reciprocatory movement to said work holding means and a work piece held thereby in a path generally transverse to the direction of movement of said wheel; said movement imparting means and work piece holding means comprising a boom extending across said wheel and disposed above said wheel a distance greater than the thickness of a work piece and having one end thereof mounted for movement about a vertical axis, work piece engaging means connected to said boom, and means comprising a vertical axis shaft and supporting bearing means therefor, means for driving said shaft, a crankpin on said shaft, and a link connecting said crankpin with the adjacent end of said boom for oscillating said boom about said pivotal mounting with resultant reciprocatory movement of a work piece held by said work piece engaging means on said lapping surface; said link being longitudinally adjustable with resultant shifting of the longitudinal position of a path of a work piece reciprocated by oscillations of said boom.

13. In a machine for lapping fiat surfaces on objects disposed with the surface thereof to be lapped resting on a moving, abrading surface, a base, a wheel disposed for 11 rotation about a vertical axis and having a flat upper surface constituting a lapping surface mounted on said base, a first heating means carried by said base and engaging said wheel and establishing only the said vertical axis of rotation of said wheel, a second hearing means carried by said base and affording vertical support for said wheel; said second bearing means comprising a series of tapered rollers each mounted on a'separate stationary base and said rollers being disposed in a circumferentially spaced relation about the axis of said wheel and with the axes of said rollers being in vertical planes radial to said axis of said wheel and being so angularly disposed in said vertical planes that the uppermost portions of the peripheries of said rollers are disposed tangentially to a common plane normal to the axis of said wheel, and a ring member on the under surface of said wheel disposed eoaxially tothe axis thereof and having a fiat bottom surface in said common horizontal plane resting on all of said rollers; said ring member having a radial dimension which is less than the radial dimension of said wheel, means for rotating said wheel, and means for holding a work piece on said lapping surface of said wheel and for imparting reciprocating movements to the work piece While resting on said rotating lapping surface.

14. In a machine for lapping fiat surfaces on objects disposed with the surface thereof to be lapped resting on a moving, abrading surface, a base, a wheel disposed for rotation about a vertical axis and having a flat upper surface constituting a lapping surface mounted on said base, a first bearing means carried by said base and engaging said wheel and establishing only the said vertical axis of rotation of said wheel, a second bearing means carried by said base and affording vertical support for said wheel; said second bearing means comprising a series of tapered rollers each mounted on a separate stationary base and said rollers being disposed in a circumferentially spaced relation about the axis of said wheel and with the axes of said rollers being in vertical planes radial to said axis of said wheel and being so angularly disposed in said vertical planes that the uppermost portions of the peripheries of said rollers are disposed tangentially to a common plane normal to the axis of said wheel, and a ring member on the under surface of said wheel disposed eoaxially to the axis thereof and having a flat bottom surface in said common horizontal plane resting on all of said rollers; said ring member having a radial dimension which is less than the radial dimension of said wheel, means for rotating said wheel, and means for holding a work piece on said lapping surface of said wheel and for imparting reciprocating movements to the work piece while resting on said rotating lapping surface; said tapered rollers being independently vertically adjustable.

15. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving, abrading surface, a base, a wheel disposed for rotation about a vertical axis and having a flat upper surface constituting a lapping surface mounted on said base, a first bearing means carried by said base and engaging said wheel and establishing only the said vertical axis of rotation of said wheel, a second bearing means carried by said base and affording vertical support for said wheel; said second bearing means comprising a series of tapered rollers each mounted on a separate stationary base and said rollers being disposed in a circumferentially spaced relation about the axis of said wheel and with the axes of said rollers being in vertical planes radial to said axis of said wheel and being so angularly disposed in said vertical planes that the uppermost portions of the peripheries of said rollers are disposed tangentially to a common plane normal to the axis of said wheel, and a ring member on the under surface of said wheel disposed coaxial-1y to the axis thereof and having a flat bottom surface in said com-mon horizontal plane resting on all of said rollers; said ring member having a radial dimension which is less than the radial dimension of said wheel, means for rotating said wheel, and means for holding a work piece on said lapping surface of said wheel and for imparting reciprocating movements to the work piece while resting on said rotating lapping surface; said upper surface of said wheel carrying a series of segmental plates constituting the lapping surface and said lapping surface being interrupted by a plurality of grooves extending radially of said wheel for the discharge of abrasive and the abrasively comminuted material of the work piece being lapped thereon.

16. In a machine for lapping flat surfaces on objects disposed with the surface thereof to be lapped resting on a moving abrading surface, a wheel mounted for rotation about a vertical axis upon hearing means disposed wholly beneath said wheel and said wheel having a flat upper surface constituting a lapping surface for work pieces placed thereon, means for rotating said wheel about said axis, means for holding a work piece on said lapping surface against rotation with said wheel, and means for imparting reciprocatory movement to said work holding means and a work piece held thereby in a path generally transverse to the direction of movement of said wheel; said movement imparting means and work piece holding means comprising a boom extending across said Wheel and disposed above said wheel a distance greater than the thickness of a work piece and having one end thereof pivotally mounted for movement about a vertical axis, work piece holding means connected to said boom, and means comprising a vertical axis shaft and supporting bearing means therefor disposed at the side of said wheel opposite said pivotal mounting of said boom, means for driving said shaft, a crank pin on said shaft, and a link connecting said crank pin with the adjacent end of said boom for oscillating said boom about said pivotal mounting with resultant reciprocatory movement of a work piece held on said lapping surface by said work piece holding means; said vertical axis shaft and bearing support therefor including means for shifting said shaft and support along a line extending transversely to said boom and for holding said shaft and support at any position to which it is moved along said line with resultant shifting of the path through which a work piece is moved by said boom longitudinally of said path without significant change in the length of said path.

References Cited in the file of this patent UNITED STATES PATENTS 125,434 Battell et al Apr. 9, 1872 543,076 Bannister July 23, 1895 983,517 Ratcliffe Feb. 7, 1911 1,101,046 Valentine June 23, 1914 1,121,995 Elvers Dec. 22, 1914 1,733,295 Crowley Oct. 29, 1929 1,805,254 Osborn May 12, 1931 2,036,841 Trysell Apr. 7, 1936 2,391,388 Bullard Dec. 25, 1945 2,404,282 Fruth July 16, 1946 FOREIGN PATENTS 9,481 Great Britain Apr. 21, 1909 

